Fungal osteomyelitis of the axial border of the proximal sesamoid bones in a horse.

The study reports on a case of a 12-year old horse diagnosed with fungal osteomyelitis, a bone infection caused by a certain fungus, detecting Aspergillus fumigatus from the synovial fluid of the animal. After various treatments, although the horse showed signs of considerable improvement, it was eventually retired due to persistent mild lameness and the prospect of unimproving osteoarthritis.

Case Presentation and Diagnosis

• The subject of the study was a 12-year-old gelding Standardbred horse which had been referred due to swelling of the right metacarpophalangeal joint.
• To diagnose the condition, investigators used non-invasive imaging technologies: ultrasonography and radiography. Ultrasonography revealed hypoechoic areas (darker regions that don’t reflect ultrasound waves well) that suggested the presence of synovial fluid, while radiography showed the erosion (lysis) of the axial border of the horse’s proximal sesamoid bones.
• A fungal culture from the synovial fluid identified the culprit fungus as Aspergillus fumigatus.

Treatment and Outcome

• Doctors treated the horse initially with Regional limb perfusion, which involves administering medication (in this case, amikacin in a saline solution) directly into the blood vessels of the infected area. This procedure was performed twice over a period of 4 days after admission.
• The horse was also orally administered with the antifungal agent, Itraconazole, for approximately 9 week.
• In addition, joint lavage, a procedure involving the introduction of cleansing solution into the joint space, was performed four times; each with amikacin in a saline solution.
• Three months after discharge, even though the horse was in overall good health and gained considerable weight, it exhibited mild lameness during trotting and could not return to its previous performance level due to persistent osteoarthritis, which eventually led to its retirement from racing.

Conclusion

• The study concludes by underscoring the utility of imaging technologies and fungal cultures for diagnosing fungal osteomyelitis in horses. It also encourages considering the diagnosis of fungal osteomyelitis in horses that have been treated with intra-articular corticosteroids, as they may be at increased risk for this type of infection.